1. Field of the Invention
The present invention relates to a TFT substrate and a display device having the TFT substrate. More particularly, the present invention relates to a TFT substrate and a liquid crystal display device having the TFT substrate.
2. Description of the Related Art
A liquid crystal display (LCD) device includes a color filter substrate, a thin film transistor (TFT) substrate and a liquid crystal layer. The color filter substrate includes a color filter layer and a common electrode. The TFT substrate includes a TFT and a pixel electrode that is electrically connected to the TFT. The liquid crystal layer is disposed between the TFT substrate and the color filter substrate. When a data voltage is applied to the pixel electrode, an electric field is generated between the pixel electrode and the common electrode to alter an arrangement of liquid crystal molecules of the liquid crystal layer. As a result, an optical transmissivity is altered to display an image.
When a contrast ratio of the LCD device is high, the LCD device displays a clear image. Therefore, it would be desirable to improve the contrast ratio for LCD devices.